Solid-state imaging elements such as CMOS (Complementary Metal Oxide Semiconductor) image sensors have been widely used in digital still cameras and digital video cameras.
As an electron shutter system for CMOS image sensors, a global shutter system has been suggested (see Patent Document 1, for example). According to the global shutter system, exposure is simultaneously started for all the valid pixels for imaging, and the exposure is simultaneously ended for all the valid pixels. Therefore, to temporarily store photoelectric charges accumulated by photodiodes while reading occurs after the end of the exposure, a memory unit needs to be provided.
In this type of CMOS image sensor, a light shielding film having light shielding properties needs to be formed to shield the memory unit from light. For example, Patent Document 2 discloses a CMOS image sensor that includes a light shielding film having light shielding properties.